Sarah E Janssen
Sarah Janssen is an isotope geochemist working in the M3 Research Lab (MRL) located within the Upper Midwest Water Science Center.
She has a PhD in environmental chemistry from Rutgers University and a bachelor’s in chemistry from
University of the Sciences in Philadelphia. Her work focuses on the application of stable isotope techniques for understanding sources and transformations of mercury (Hg) in the environment. Her research interests include Hg cycling in contaminated ecosystems, the investigation of microbial Hg transformations using stable isotopes, and development of analytical methods to improve Hg isotope measurements.
Current Projects
- Mercury Cycling and Source Identification in the St Louis River Estuary MN/WI (collaboration with US EPA and Minnesota Pollution Control Agency)
- Mercury Isotope Fractionation during Microbial Uptake and Transformations of Hg (collaboration with Rutgers University and University of Ottawa)
- Method Development for the Pre-concentration of Waters and Low Concentration Environmental Samples for Mercury Isotopic Analysis
Education and Certifications
Ph.D. 2016, Environmental Chemistry, Rutgers University, New Brunswick, NJ
B.S. 2011, Chemistry, University of the Sciences, Philadelphia, PA
Science and Products
Filter Total Items: 38
Mercury Methylation Assay Along a Salinity Gradient in Coastal Peat Soils in the Florida Everglades Mercury Methylation Assay Along a Salinity Gradient in Coastal Peat Soils in the Florida Everglades
This data was collected as part of a laboratory study examining the effects of sea level rise on mercury (Hg) methylation and demethylation rates in peat cores collected from the Florida Everglades. Peat cores were collected from a freshwater region of the Everglades, Water Conservation Area 3, in 2022 and taken to the University of California-Davis for methylation and demethylation...
Mercury in soil, water, sediment, and biota in headwater streams associated with wildfires in the northwestern U.S., 2021-2022 Mercury in soil, water, sediment, and biota in headwater streams associated with wildfires in the northwestern U.S., 2021-2022
Comma-separated values (.csv) files containing data related to mercury in soil, water, sediment, in-stream leaf litter, periphyton, and aquatic invertebrates collected in 2021-2022 from headwater streams associated with wildfires in the northwestern U.S.
Mercury Stable Isotope Assessment of Dragonflies and Fish Tissues across United States National Parks Mercury Stable Isotope Assessment of Dragonflies and Fish Tissues across United States National Parks
This dataset details mercury (Hg) stable isotope values in dragonflies and fish tissues collected across U.S. National Parks. Dragonfly samples were collected as part of the Dragonfly Mercury Project (https://geonarrative.usgs.gov/dmp/), a citizen science project focused on using dragonfly larvae as biosentinels for Hg bioaccumulation. Fish were collected as part of separate park-wide...
Walleye (Sander vitreus), Yellow Perch (Perca flavescens) and Surface Water Mercury Concentrations in Minnesota Lakes Walleye (Sander vitreus), Yellow Perch (Perca flavescens) and Surface Water Mercury Concentrations in Minnesota Lakes
Water quality and fish tissue samples were collected and measured for mercury concentrations in a total of 23 small to medium size lakes in Minnesota to assess the impact that zebra mussel (Dreissena polymorpha) invasion had on mercury bioaccumulation. Water samples were collected in October and November of 2021 from 22 lakes and analyzed for total mercury, methylmercury, dissolved...
Great Lakes Sediment Surveillance Program: Mercury Concentrations and Mercury Stable Isotopes in Sediments of the Laurentian Great Lakes Great Lakes Sediment Surveillance Program: Mercury Concentrations and Mercury Stable Isotopes in Sediments of the Laurentian Great Lakes
As part of the larger Great Lakes Sediment Surveillance Program (GLSSP), the U.S. Geological Survey Mercury Research Laboratory (MRL) partnered with the U.S. Environmental Protection Agency and the University of Minnesota-Duluth to assess contaminant concentrations within surface sediments and sediment cores from the Laurentian Great Lakes. Sediments were assessed for mercury...
Measurements of mercury stable isotopes during planktonic uptake and photochemical demethylation of methylmercury Measurements of mercury stable isotopes during planktonic uptake and photochemical demethylation of methylmercury
Laboratory experiments were performed between 2019 and 2020 to examine how dissolved organic matter (DOM) and phytoplankton (Raphidocelis subcapitata) cells alter mercury (Hg) uptake and isotope fractionation. Experiments were performed at ambient Hg to thiol ratios using natural organic matter isolates received from collaborators at the University of California-Davis. Two types of...
Filter Total Items: 50
Seasonal stratification drives bioaccumulation of pelagic mercury sources in eutrophic lakes Seasonal stratification drives bioaccumulation of pelagic mercury sources in eutrophic lakes
Increased lake eutrophication, influenced by changing climate and land use, alters aquatic cycling and bioaccumulation of mercury (Hg). Additionally, seasonally dynamic lake circulation and plankton community composition can confound our ability to predict changes in biological Hg concentrations and sources. To assess temporal variation, we examined seasonal total Hg (THg) and...
Authors
Grace Jane Armstrong, Sarah Elizabeth Janssen, Ryan F. Lepak, Tylor Rosera, Benjamin D. Peterson, Samia T. Cushing, Michael Tate, James W. Hurley
Sulfate reduction drives elevated methylmercury formation in water column of eutrophic freshwater lake Sulfate reduction drives elevated methylmercury formation in water column of eutrophic freshwater lake
Mercury (Hg) contamination of aquatic food webs is controlled in part by the formation and accumulation of toxic and bioaccumulative methylmercury (MeHg). MeHg production is mediated by metabolically diverse microorganisms carrying the hgcAB gene pair, while the demethylation reaction is mediated by several biotic and abiotic processes. However, the relative importance of these two...
Authors
Benjamin D. Peterson, Sarah E. Janssen, Brett A. Poulin, Jacob M. Ogorek, Amber White, Elizabeth A. McDaniel, Robert A. Marick, Grace Jane Armstrong, Nicholas D. Scheel, Michael T. Tate, David P. Krabbenhoft, Katherine D. McMahon
Mercury speciation and stable isotopes in emperor penguins: First evidence for biochemical demethylation of methylmercury to mercury-dithiolate and mercury-tetraselenolate complexes Mercury speciation and stable isotopes in emperor penguins: First evidence for biochemical demethylation of methylmercury to mercury-dithiolate and mercury-tetraselenolate complexes
Apex marine predators, such as toothed whales and large petrels and albatrosses, ingest mercury (Hg) primarily in the form of methylmercury (MeHg) via prey consumption, which they detoxify as tiemannite (HgSe). One of the most intriguing current questions in Hg research is how more abundant lower trophic level predators detoxify MeHg, particularly in marine environments where tissue Hg...
Authors
Alain Manceau, Paco Bustamante, Etienne Richy, Yves Cherel, Sarah E. Janssen, Pieter Glatzel, Brett A. Poulin
New tools for a legacy problem: How isotope tracers inform area of concern actions in the St. Louis River in Lake Superior New tools for a legacy problem: How isotope tracers inform area of concern actions in the St. Louis River in Lake Superior
Numerous mercury (Hg) sources can contribute to biological burdens within the Great Lakes, including atmospheric deposition (e.g., precipitation), non-point source land runoff (e.g., watershed), and legacy contamination. Due to these different environmental entry points, it is often difficult to ascertain if legacy Hg contamination contributes to contemporary fish consumption advisories...
Authors
Sarah E. Janssen, Joel C. Hoffman, David P. Krabbenhoft
Using mercury and lead stable isotopes to assess mercury, lead, and trace metal source contributions to Great Salt Lake, Utah, USA Using mercury and lead stable isotopes to assess mercury, lead, and trace metal source contributions to Great Salt Lake, Utah, USA
Great Salt Lake is a critical habitat for migratory birds that is threatened by elevated metal concentrations, including mercury (Hg) and lead (Pb), and is subject to severe hydrologic changes, such as declining lake level. When assessing metal profiles recorded in Great Salt Lake sediment, a large data gap exists regarding the sources of metals within the system, which is complicated by...
Authors
Samuel Francisco Lopez, Sarah E. Janssen, Michael T. Tate, Diego P. Fernandez, Christopher R. Anderson, Grace Jane Armstrong, Thomas Charng-Shuen Wang, William P. Johnson
Increased mercury concentrations in walleye and yellow perch in lakes invaded by zebra mussels Increased mercury concentrations in walleye and yellow perch in lakes invaded by zebra mussels
Zebra mussels (Dreissena polymorpha) are invasive species that alter ecosystems and food webs with the potential to affect aquatic mercury cycling and bioaccumulation in fishes, although the effect of zebra mussels on fish tissue mercury has not been tested in inland lakes. We assessed differences in fish tissue mercury concentrations and food webs in Minnesota lakes with and without...
Authors
Naomi S. Blinick, Denver Link, Tyler D. Ahrenstoroff, Bethany J. Bethke, Abram B. Fleishman, Sarah E. Janssen, David P. Krabbenhoft, Jenna K.R. Nelson, Heidi M. Rantala, Claire L. Rude, Gretchen J.A. Hansen
Non-USGS Publications**
Janssen, S.E.; Johnson, M.W.; Blum, J.D.; Barkay, T.; Reinfelder, J.R., Separation of monomethylmercury from estuarine sediments for mercury isotope analysis. Chemical Geology 2015
Janssen, S.E.; Schaefer, J.K.; Barkay, T.; Reinfelder, J.R. Fractionation of mercury stable isotopes during microbial methylmercury production in pure culture. Environ. Sci. Technol. 2016
Lloyd, N.; Janssen, S.E.; Reinfelder J.R.; Barkay, T., Exposure to mercury selects for antibiotic resistance in Fundulus heteroclitus gut microbiome, Current Microbiology, 2016
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
Filter Total Items: 38
Mercury Methylation Assay Along a Salinity Gradient in Coastal Peat Soils in the Florida Everglades Mercury Methylation Assay Along a Salinity Gradient in Coastal Peat Soils in the Florida Everglades
This data was collected as part of a laboratory study examining the effects of sea level rise on mercury (Hg) methylation and demethylation rates in peat cores collected from the Florida Everglades. Peat cores were collected from a freshwater region of the Everglades, Water Conservation Area 3, in 2022 and taken to the University of California-Davis for methylation and demethylation...
Mercury in soil, water, sediment, and biota in headwater streams associated with wildfires in the northwestern U.S., 2021-2022 Mercury in soil, water, sediment, and biota in headwater streams associated with wildfires in the northwestern U.S., 2021-2022
Comma-separated values (.csv) files containing data related to mercury in soil, water, sediment, in-stream leaf litter, periphyton, and aquatic invertebrates collected in 2021-2022 from headwater streams associated with wildfires in the northwestern U.S.
Mercury Stable Isotope Assessment of Dragonflies and Fish Tissues across United States National Parks Mercury Stable Isotope Assessment of Dragonflies and Fish Tissues across United States National Parks
This dataset details mercury (Hg) stable isotope values in dragonflies and fish tissues collected across U.S. National Parks. Dragonfly samples were collected as part of the Dragonfly Mercury Project (https://geonarrative.usgs.gov/dmp/), a citizen science project focused on using dragonfly larvae as biosentinels for Hg bioaccumulation. Fish were collected as part of separate park-wide...
Walleye (Sander vitreus), Yellow Perch (Perca flavescens) and Surface Water Mercury Concentrations in Minnesota Lakes Walleye (Sander vitreus), Yellow Perch (Perca flavescens) and Surface Water Mercury Concentrations in Minnesota Lakes
Water quality and fish tissue samples were collected and measured for mercury concentrations in a total of 23 small to medium size lakes in Minnesota to assess the impact that zebra mussel (Dreissena polymorpha) invasion had on mercury bioaccumulation. Water samples were collected in October and November of 2021 from 22 lakes and analyzed for total mercury, methylmercury, dissolved...
Great Lakes Sediment Surveillance Program: Mercury Concentrations and Mercury Stable Isotopes in Sediments of the Laurentian Great Lakes Great Lakes Sediment Surveillance Program: Mercury Concentrations and Mercury Stable Isotopes in Sediments of the Laurentian Great Lakes
As part of the larger Great Lakes Sediment Surveillance Program (GLSSP), the U.S. Geological Survey Mercury Research Laboratory (MRL) partnered with the U.S. Environmental Protection Agency and the University of Minnesota-Duluth to assess contaminant concentrations within surface sediments and sediment cores from the Laurentian Great Lakes. Sediments were assessed for mercury...
Measurements of mercury stable isotopes during planktonic uptake and photochemical demethylation of methylmercury Measurements of mercury stable isotopes during planktonic uptake and photochemical demethylation of methylmercury
Laboratory experiments were performed between 2019 and 2020 to examine how dissolved organic matter (DOM) and phytoplankton (Raphidocelis subcapitata) cells alter mercury (Hg) uptake and isotope fractionation. Experiments were performed at ambient Hg to thiol ratios using natural organic matter isolates received from collaborators at the University of California-Davis. Two types of...
Filter Total Items: 50
Seasonal stratification drives bioaccumulation of pelagic mercury sources in eutrophic lakes Seasonal stratification drives bioaccumulation of pelagic mercury sources in eutrophic lakes
Increased lake eutrophication, influenced by changing climate and land use, alters aquatic cycling and bioaccumulation of mercury (Hg). Additionally, seasonally dynamic lake circulation and plankton community composition can confound our ability to predict changes in biological Hg concentrations and sources. To assess temporal variation, we examined seasonal total Hg (THg) and...
Authors
Grace Jane Armstrong, Sarah Elizabeth Janssen, Ryan F. Lepak, Tylor Rosera, Benjamin D. Peterson, Samia T. Cushing, Michael Tate, James W. Hurley
Sulfate reduction drives elevated methylmercury formation in water column of eutrophic freshwater lake Sulfate reduction drives elevated methylmercury formation in water column of eutrophic freshwater lake
Mercury (Hg) contamination of aquatic food webs is controlled in part by the formation and accumulation of toxic and bioaccumulative methylmercury (MeHg). MeHg production is mediated by metabolically diverse microorganisms carrying the hgcAB gene pair, while the demethylation reaction is mediated by several biotic and abiotic processes. However, the relative importance of these two...
Authors
Benjamin D. Peterson, Sarah E. Janssen, Brett A. Poulin, Jacob M. Ogorek, Amber White, Elizabeth A. McDaniel, Robert A. Marick, Grace Jane Armstrong, Nicholas D. Scheel, Michael T. Tate, David P. Krabbenhoft, Katherine D. McMahon
Mercury speciation and stable isotopes in emperor penguins: First evidence for biochemical demethylation of methylmercury to mercury-dithiolate and mercury-tetraselenolate complexes Mercury speciation and stable isotopes in emperor penguins: First evidence for biochemical demethylation of methylmercury to mercury-dithiolate and mercury-tetraselenolate complexes
Apex marine predators, such as toothed whales and large petrels and albatrosses, ingest mercury (Hg) primarily in the form of methylmercury (MeHg) via prey consumption, which they detoxify as tiemannite (HgSe). One of the most intriguing current questions in Hg research is how more abundant lower trophic level predators detoxify MeHg, particularly in marine environments where tissue Hg...
Authors
Alain Manceau, Paco Bustamante, Etienne Richy, Yves Cherel, Sarah E. Janssen, Pieter Glatzel, Brett A. Poulin
New tools for a legacy problem: How isotope tracers inform area of concern actions in the St. Louis River in Lake Superior New tools for a legacy problem: How isotope tracers inform area of concern actions in the St. Louis River in Lake Superior
Numerous mercury (Hg) sources can contribute to biological burdens within the Great Lakes, including atmospheric deposition (e.g., precipitation), non-point source land runoff (e.g., watershed), and legacy contamination. Due to these different environmental entry points, it is often difficult to ascertain if legacy Hg contamination contributes to contemporary fish consumption advisories...
Authors
Sarah E. Janssen, Joel C. Hoffman, David P. Krabbenhoft
Using mercury and lead stable isotopes to assess mercury, lead, and trace metal source contributions to Great Salt Lake, Utah, USA Using mercury and lead stable isotopes to assess mercury, lead, and trace metal source contributions to Great Salt Lake, Utah, USA
Great Salt Lake is a critical habitat for migratory birds that is threatened by elevated metal concentrations, including mercury (Hg) and lead (Pb), and is subject to severe hydrologic changes, such as declining lake level. When assessing metal profiles recorded in Great Salt Lake sediment, a large data gap exists regarding the sources of metals within the system, which is complicated by...
Authors
Samuel Francisco Lopez, Sarah E. Janssen, Michael T. Tate, Diego P. Fernandez, Christopher R. Anderson, Grace Jane Armstrong, Thomas Charng-Shuen Wang, William P. Johnson
Increased mercury concentrations in walleye and yellow perch in lakes invaded by zebra mussels Increased mercury concentrations in walleye and yellow perch in lakes invaded by zebra mussels
Zebra mussels (Dreissena polymorpha) are invasive species that alter ecosystems and food webs with the potential to affect aquatic mercury cycling and bioaccumulation in fishes, although the effect of zebra mussels on fish tissue mercury has not been tested in inland lakes. We assessed differences in fish tissue mercury concentrations and food webs in Minnesota lakes with and without...
Authors
Naomi S. Blinick, Denver Link, Tyler D. Ahrenstoroff, Bethany J. Bethke, Abram B. Fleishman, Sarah E. Janssen, David P. Krabbenhoft, Jenna K.R. Nelson, Heidi M. Rantala, Claire L. Rude, Gretchen J.A. Hansen
Non-USGS Publications**
Janssen, S.E.; Johnson, M.W.; Blum, J.D.; Barkay, T.; Reinfelder, J.R., Separation of monomethylmercury from estuarine sediments for mercury isotope analysis. Chemical Geology 2015
Janssen, S.E.; Schaefer, J.K.; Barkay, T.; Reinfelder, J.R. Fractionation of mercury stable isotopes during microbial methylmercury production in pure culture. Environ. Sci. Technol. 2016
Lloyd, N.; Janssen, S.E.; Reinfelder J.R.; Barkay, T., Exposure to mercury selects for antibiotic resistance in Fundulus heteroclitus gut microbiome, Current Microbiology, 2016
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.